In general the present invention relates to thermostatic systems and more particularly to heating and/or cooling systems that are turned "on" and "off" by electrical contacts operated by a thermal-sensitive element.
Although the present invention has many applications, it is particularly useful as an energy saving device for operating thermostatically controlled furnaces in homes and apartments that are vacant by reason of being held for sale or rent. In colder climates, particularly in the winter, it is desirable to maintain a predetermined minimum temperature within the house or apartment to protect its plumbing system from freezing, and this is usually accomplished by activating the furnace system and setting the standard thermostat control unit to the predetermined minimum temperature. When the premises are occupied for brief periods of time, such as during an inspection by a realtor and/or potential purchasers or renters, it is likely that the thermostat control unit will be turned up to warm the premises to a comfort temperature level, such as 70.degree. F., with the intention of restoring the temperature setting to its minimum level when leaving.
Unfortunately, the control unit many times is not returned to the minimum temperature setting, and the house or apartment may remain vacant for days and even weeks, with the furnace being operated at the higher temperature range, thus causing a great waste of energy and a substantial expense to the owner of the building. For a builder of new houses, who maintains an inventory of vacant, "for sale" houses, the monthly expense due to unnecessary heating, becomes exorbitant, especially in view of the rising cost of electricity and fuel.
Although the present invention is described herein in conjunction with a thermostatically-controlled furnace, it will be appreciated that the same principles of operation apply to a thermostatically controlled air-conditioning or cooling system for homes, apartments and other buildings. Thus, the present invention is useful in combination with these latter systems also.
It is therefore an object of the present invention to provide method and apparatus for saving energy (and the correlative cost thereof) in operating thermostatically regulated heating or cooling systems which for the most part are to be operated at a temperature level that consumes minimal energy, and which occasionally are to be operated for brief intervals at a temperature which requires a greater consumption of energy.
Another object is to provide method and apparatus for use in conjunction with a conventional thermostatically regulated home heating/cooling system in which the standard thermostat control unit can be temporarily replaced by a modified control unit during vacancy of the building which modified unit has a normal operating mode for maintaining the temperature of the vacant building at a predetermined level requiring only minimal energy consumption, and which has a different, manually actuated mode, to be used when the premises are occupied for a brief period, for changing the temperature level to a range that is comfortable to the occupants but consumes more energy, where the last named mode is self-expiring, to cause the system to automatically revert to the normal operating mode to insure that the system is not neglectfully left in its higher energy consuming state.
A further object of the present invention is to provide a low cost, easily manufactured, modified thermostat control unit, that may be substituted for a standard control unit in a vacant house or apartment that is for sale or rent, to enable the setting of the device at a temperature range that minimizes the "on" operation of the heating or cooling system, and which enables the system to be manually changed to a different temperature range (increased in case of a heating system and decreased in the case of a cooling or air conditioning system) for the duration of a brief period of inspection of the premises by prospective renters or buyers, and which automatically reverts to the first mentioned temperature range after a predetermined, short interval.